PGO was a hit with people outside of the fanbase so I can see the same here.
Was it though? It may have been a hit with people outside of the current Pokemon fanbase, but I expect a large chunk, if not all of them, were a part of the fanbase at some point. Nostalgia was a big part of what made Pokemon Go such a huge success. There's a tonne of people out there who fondly remember gen 1 Pokemon.
As for Animal Crossing, I think that really depends on how it's initially received. A good reception and good word of mouth give it a very good chance of people outside the fanbase going for it as well. If it fails at those things, then it's probably going to have to rely on the existing AC fanbase.